This invention relates to dip tanks for treating generally rectangular packages of lumber or similar work product, and deals more particularly with a hoist for lowering and raising the packages into and out of the tank.
The hoist of this invention was conceived for use in treating packages of lumber with a liquid agent and is therefore shown and described herein as applied to such use. It should be understood, however, that the hoist is not necessarily limited to handling packages of lumber and can be used with other products capable of being assembled into relatively large packages or bundles.
In the case of white pine, for example, lumber is susceptible to attack by a fungus which discolors it, producing blue stain. To prevent this blue stain it has been customary in the past to spray white pine lumber with a liquid fungicide. This spray, however, is somewhat difficult to control and, despite precautions, tends to come into contact with people and to pollute work areas.
The hoist of the invention overcomes the problem of treating lumber with a chemical spray by enabling packages of lumber to be conveniently dipped in a tank of liquid fungicide or other treatment agent.
It is therefore an object of the invention to provide a hoist mechanism for use in raising and lowering relatively large packages or bundles of work product into and out of an associated dip tank and which hoist mechanism is of a simple, rugged and reliable construction.
Another object of the invention is to provide a hoist mechanism of the foregoing character having an associated control system such that after a package is placed on the hoist and a push button pressed, the hoist will automatically undergo a full cycle of operation without further attention.
A still further object of the invention is to provide a hoist mechanism which is hydraulically operated and wherein the pump for the hydraulic system is driven only at times when hydraulic power is needed.
Other objects and advantages of the invention will be apparent from the drawings and from the following detailed description thereof.